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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Impact of Surface Roughness and Soil Texture on Mineral Dust Emission Fluxes Modeling

Dust production models (DPM) used to estimate vertical fluxes of mineral dust aerosols over arid regions need accurate data on soil and surface properties. The Laboratoire Inter-Universitaire des Systemes Atmospheriques (LISA) data set was developed for Northern Africa, the Middle East, and East Asia. This regional data set was built through dedicated field campaigns and include, among others, the aerodynamic roughness length, the smooth roughness length of the erodible fraction of the surface, and the dry (undisturbed) soil size distribution. Recently, satellite-derived roughness length and high-resolution soil texture data sets at the global scale have emerged and provide the opportunity for the use of advanced schemes in global models. This paper analyzes the behavior of the ERS satellite-derived global roughness length and the State Soil Geographic data base-Food and Agriculture Organization of the United Nations (STATSGO-FAO) soil texture data set (based on wet techniques) using an advanced DPM in comparison to the LISA data set over Northern Africa and the Middle East. We explore the sensitivity of the drag partition scheme (a critical component of the DPM) and of the dust vertical fluxes (intensity and spatial patterns) to the roughness length and soil texture data sets. We also compare the use of the drag partition scheme to a widely used preferential source approach in global models. Idealized experiments with prescribed wind speeds show that the ERS and STATSGO-FAO data sets provide realistic spatial patterns of dust emission and friction velocity thresholds in the region. Finally, we evaluate a dust transport model for the period of March to July 2011 with observed aerosol optical depths from Aerosol Robotic Network sites. Results show that ERS and STATSGO-FAO provide realistic simulations in the region.

textures↗
NASA NTRS2014

Operations of Suborbital Research Platforms to Obtain Remote Sensing Data

The Armstrong Flight Research Center (AFRC) operates six highly modified aircraft in support the NASA science mission.These include two ER-2 aircraft, a DC-8, a G-III, and two Global Hawks. The NASA science missions demands that these aircraft be deployed around the globe while carrying a variety of science instruments. The ER-2 reconnaissance aircraft provides routine access to altitudes over 70,000 ft (20km) for large payloads and with an endurance of over 10hours. Recently the ER-2s have conducted convective storm research missions in the mid-western United States and supported the development of new instruments. The DC-8 is a four-engine jetliner that operates for up to 12 hours ataltitudes that range from the surface to 42,000 ft (13 km). Although its flight envelope is equivalent to conventional.

unmanned aerial platforms↗
NASA NTRS2015

Real-Time Kennedy Space Center and Cape Canaveral Air Force Station High-Resolution Model Implementation and Verification

NASA's Launch Services Program, Ground Systems Development and Operations, Space Launch System and other programs at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) use the daily and weekly weather forecasts issued by the 45th Weather Squadron (45 WS) as decision tools for their day-to-day and launch operations on the Eastern Range (ER). Examples include determining if they need to limit activities such as vehicle transport to the launch pad, protect people, structures or exposed launch vehicles given a threat of severe weather, or reschedule other critical operations. The 45 WS uses numerical weather prediction models as a guide for these weather forecasts, particularly the Air Force Weather Agency (AFWA) 1.67 km Weather Research and Forecasting (WRF) model. Considering the 45 WS forecasters' and Launch Weather Officers' (LWO) extensive use of the AFWA model, the 45 WS proposed a task at the September 2013 Applied Meteorology Unit (AMU) Tasking Meeting requesting the AMU verify this model. Due to the lack of archived model data available from AFWA, verification is not yet possible. Instead, the AMU proposed to implement and verify the performance of an ER version of the high-resolution WRF Environmental Modeling System (EMS) model configured by the AMU (Watson 2013) in real time. Implementing a real-time version of the ER WRF-EMS would generate a larger database of model output than in the previous AMU task for determining model performance, and allows the AMU more control over and access to the model output archive. The tasking group agreed to this proposal; therefore the AMU implemented the WRF-EMS model on the second of two NASA AMU modeling clusters. The AMU also calculated verification statistics to determine model performance compared to observational data. Finally, the AMU made the model output available on the AMU Advanced Weather Interactive Processing System II (AWIPS II) servers, which allows the 45 WS and AMU staff to customize the model output display on the AMU and Range Weather Operations (RWO) AWIPS II client computers and conduct real-time subjective analyses.

Meteorology↗
NASA NTRS2015

High-Resolution Mesoscale Model Setup for the Eastern Range and Wallops Flight Facility

Mesoscale weather conditions can have an adverse effect on space launch, landing, ground processing, and weather advisories, watches, and warnings at the Eastern Range (ER) in Florida and Wallops Flight Facility (WFF) in Virginia. During summer, land-sea interactions across Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) lead to sea breeze front formation, which can spawn deep convection that can hinder operations and endanger personnel and resources. Many other weak locally-driven low-level boundaries and their interactions with the sea breeze front and each other can also initiate deep convection in the KSC/CCAFS area. These convective processes often last 60 minutes or less and pose a significant challenge to the local forecasters. Surface winds during the transition seasons (spring and fall) pose the most difficulties for the forecasters at WFF. They also encounter problems forecasting convective activity and temperature during those seasons. Therefore, accurate mesoscale model forecasts are needed to better forecast a variety of unique weather phenomena. Global and national scale models cannot properly resolve important local-scale weather features at each location due to their horizontal resolutions being much too coarse. Therefore, a properly tuned local data assimilation (DA) and forecast model at a high resolution is needed to provide improved capability. To accomplish this, a number of sensitivity tests were performed using the Weather Research and Forecasting (WRF) model in order to determine the best DA/model configuration for operational use at each of the space launch ranges to best predict winds, precipitation, and temperature. A set of Perl scripts to run the Gridpoint Statistical Interpolation (GSI)/WRF in real-time were provided by NASA's Short-term Prediction Research and Transition Center (SPoRT). The GSI can analyze many types of observational data including satellite, radar, and conventional data. The GSI/WRF scripts use a cycled GSI system similar to the operational North American Mesoscale (NAM) model. The scripts run a 12-hour pre-cycle in which data are assimilated from 12 hours prior up to the model initialization time. A number of different model configurations were tested for both the ER and WFF by varying the horizontal resolution on which the data assimilation was done. Three different grid configurations were run for the ER and two configurations were run for WFF for archive cases from 27 Aug 2013 through 10 Nov 2013. To quantify model performance, standard model output will be compared to the Meteorological Assimilation Data Ingest System (MADIS) data. The MADIS observation data will be compared to the WRF forecasts using the Model Evaluation Tools (MET) verification package. In addition, the National Centers for Environmental Prediction's Stage IV precipitation data will be used to validate the WRF precipitation forecasts. The author will summarize the relative skill of the various WRF configurations and how each configuration behaves relative to the others, as well as determine the best model configuration for each space launch range.

Watson, Leela R.↗
NASA NTRS2017

Analysis of Rawinsonde Spatial Separation for Space Launch Vehicle Applications at the Eastern Range

Space launch vehicles use day-of-launch steering commands based upon the upper-level (UL) atmospheric environments in order to alleviate wind induced structural loading and optimize ascent trajectory. Historically, UL wind measurements to support launch operations at the National Aeronautics and Space Administration's (NASA) Kennedy Space Center (KSC), co-located on the United States Air Force's Eastern Range (ER) at the Cape Canaveral Air Force Station use high-resolution (HR) rawinsondes. One inherent limitation with rawinsondes is the approximately one-hour sampling time necessary to measure tropospheric winds. Additionally, rawinsonde drift during ascent due to the ambient wind environment can result in the balloon being hundreds of kilometers down range, which results in questioning whether the measured winds represent the wind environment the vehicle will experience during ascent. This paper will describe the use of balloon profile databases to statistically assess the drift distance away from the ER launch complexes during HR rawinsonde ascent as a function of season. Will also discuss an alternative method to measure UL wind environments in closer proximity to the vehicle trajectory when launching from the ER.

Decker, Ryan K.↗
NASA NTRS2017

Analysis of Rawinsonde Spatial Separation for Space Launch Vehicle Applications at the Eastern Range

Space launch vehicles develop day-of-launch steering commands based upon the upper-level atmospheric environments in order to alleviate wind induced structural loading and optimize ascent trajectory. Historically, upper-level wind measurements to support launch operations at the National Aeronautics and Space Administration's (NASA's) Kennedy Space Center co-located on the United States Air Force's Eastern Range (ER) at the Cape Canaveral Air Force Station use high-resolution rawinsondes. One inherent limitation with rawinsondes consists of taking approximately one hour to generate a vertically complete wind profile. Additionally, rawinsonde drift during ascent by the ambient wind environment can result in the balloon being hundreds of kilometers down range, which results in questioning whether the measured winds represent the wind environment the vehicle will experience during ascent. This paper will describe the use of balloon profile databases to statistically assess the drift distance away from the ER launch complexes during rawinsonde ascent as a function of season and discuss an alternative method to measure upper level wind environments in closer proximity to the vehicle trajectory launching from the ER.

Decker, Ryan K.↗
NASA NTRS2018

Building a QC Database of Meteorological Data from NASA KSC and the United States Air Force's Eastern Range

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) Natural Environments Branch (EV44) provides atmospheric databases and analysis in support of space vehicle design and day-of-launch operations for NASA and commercial launch vehicle programs launching from the NASA Kennedy Space Center (KSC), co-located on the United States Air Force's Eastern Range (ER) at the Cape Canaveral Air Force Station. The ER complex is one of the most heavily instrumented sites in the United States with over 31 towers measuring various atmospheric parameters on a continuous basis. An inherent challenge with large datasets consists of ensuring erroneous data are removed from databases, and thus excluded from launch vehicle design analyses. EV44 has put forth great effort in developing quality control (QC) procedures for individual meteorological instruments, however no standard QC procedures for all databases currently exists resulting in QC databases that have inconsistencies in variables, development methodologies, and periods of record. The goal of this activity is to use the previous efforts to develop a standardized set of QC procedures from which to build meteorological databases from KSC and the ER, while maintaining open communication with end users from the launch community to develop ways to improve, adapt and grow the QC database. Details of the QC procedures will be described. As the rate of launches increases with additional launch vehicle programs, It is becoming more important that weather databases are continually updated and checked for data quality before use in launch vehicle design and certification analyses.

Brenton, J. C.↗
NASA NTRS2018

Building a Quality Controlled Database of Meteorological Data from NASA Kennedy Space Center and the United States Air Force's Eastern Range

The National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC) Natural Environments Branch (EV44) has provided atmospheric databases and analysis in support of space vehicle design and day-of-launch operations for NASA and commercial launch vehicle programs launching from the NASA Kennedy Space Center (KSC), co-located on the United States Air Force's Eastern Range (ER) at the Cape Canaveral Air Force Station. The ER complex is one of the most heavily instrumented sites in the United States with over 31 towers measuring various atmospheric parameters on a continuous basis. An inherent challenge with large sets of data consists of ensuring erroneous data is removed from databases, and thus excluded from launch vehicle design analyses. EV44 has put forth great effort in developing quality control (QC) procedures for individual meteorological instruments, however no standard QC procedures for all databases currently exists resulting in QC databases that have inconsistencies in variables, methodologies, and periods of record. The goal of this activity is to use the previous efforts by EV44 to develop a standardized set of QC procedures from which to build meteorological databases from KSC and the ER, while maintaining open communication with end users from the launch community to develop ways to improve, adapt and grow the QC database. Details of the QC procedures will be described. As the rate of launches increases with additional launch vehicle programs, it is becoming more important that weather databases are continually updated and checked for data quality before use in launch vehicle design and certification analyses.

Brenton, James C.↗
NASA NTRS2018

Modeling the Effect of Damage on the Electrical Resistivity of Melt-Infiltrated SiC/SiC Composites

Electrical resistivity (ER) measurements are a possible health monitoring technique for CMC components in future aerospace applications. In order to use ER measurements to detect and identify damage, it is necessary to understand how each specific damage state will affect the ER response. In this paper, finite element models are developed and applied to quantify the effect of specific damage states on the electrical resistivity response in a melt-infiltrated silicon carbide (SiC) fiber-reinforced silicon carbide composite. The electrical resistivity of several damage states are calculated by simulating the electric current flow through the damaged micro-structure. This is achieved by performing the numerical solution of the steady-state conservation of charge density equation. Numerical results reveal that cracking of the inter-tow matrix has the most profound effect on the composite electrical resistivity. Also, fiber/matrix debonding at matrix cracks in the 0° tows (tows aligned with the loading direction) may cause a significant increase in the electrical resistivity, but only if the fiber coating resistivity is 1000 Ω-cm or less. Cracks in the 90° tows and the crack opening displacement have very little effect on the composite electrical resistivity.

finite element analysis↗
NASA NTRS1996

Advanced Techniques for Improving Wind Direction Ambiguity Removal in Scatterometry

The ambiguity removal algorithm currently planned for NSCAT utilizes a simple median filter?? will discuss techniques of ambiguity removal and outline two new algorithms which can be used to improve ambiguity removal performance without the inclusion of additional wind field information. The techniques are applied to simulated NSCAT data but can be generalized to other scatterometer instruments such as the ERS-1 and ERS-2 scatterometers, and Sea Winds to be launched aboard ADEOS-II in 1999.

ambiguity↗
NASA NTRS2016

Transiting Exoplanet Studies and Community Targets for JWST's Early Release Science Program

The James Webb Space Telescope (JWST) will likely revolutionize transiting exoplanet atmospheric science, due to a combination of its capability for continuous, long duration observations and its larger collecting area, spectral coverage, and spectral resolution compared to existing space-based facilities. However, it is unclear precisely how well JWST will perform and which of its myriad instruments and observing modes will be best suited for transiting exoplanet studies. In this article, we describe a prefatory JWST Early Release Science (ERS) Cycle 1 program that focuses on testing specific observing modes to quickly give the community the data and experience it needs to plan more efficient and successful transiting exoplanet characterization programs in later cycles. We propose a multi-pronged approach wherein one aspect of the program focuses on observing transits of a single target with all of the recommended observing modes to identify and understand potential systematics, compare transmission spectra at overlapping and neighboring wavelength regions, confirm throughputs, and determine overall performances. In our search for transiting exoplanets that are well suited to achieving these goals, we identify 12 objects (dubbed community targets'') that meet our defined criteria. Currently, the most favorable target is WASP-62b because of its large predicted signal size, relatively bright host star, and location in JWST's continuous viewing zone. Since most of the community targets do not have well-characterized atmospheres, we recommend initiating preparatory observing programs to determine the presence of obscuring clouds/hazes within their atmospheres. Measurable spectroscopic features are needed to establish the optimal resolution and wavelength regions for exoplanet characterization. Other initiatives from our proposed ERS program include testing the instrument brightness limits and performing phase-curve observations. The latter are a unique challenge compared to transit observations because of their significantly longer durations. Using only a single mode, we propose to observe a full-orbit phase curve of one of the previously characterized, short-orbital-period planets to evaluate the facility-level aspects of long, uninterrupted time-series observations.

JWST Early Release Science (ERS)↗
NASA NTRS1973

The cosmic gamma-ray spectrum between 0.3 and 27 MeV measured on Apollo 15.

Results of new measurements of the total cosmic gamma-ray spectrum in the 0.3- to 27-MeV range obtained on Apollo 15. These data were obtained with an isotropic scintillation counter similar to that used on Ranger 3 and ERS-18. The new high-precision data permit extension and clarification of the spectrum above 1 MeV, where recent balloon and earth-satellite observations have caused doubts as to the validity of the ERS-18 data.

Trombka, J. I.↗
NASA NTRS1974

The economic value of remote sensing of earth resources from space: An ERTS overview and the value of continuity of service. Volume 10: Industry

The economic benefits of an ERS system in the area of industrial resources are discussed. Contributions of ERTS imagery to the improvement of shipping routes, detection of previously unknown and potentially active faults in construction areas, and monitoring industrial pollution are described. Due to lack of economic research concerning the subject of ERS applications in this resource area the benefit estimations reported are regarded as tentative and preliminary.

Lietzke, K. R.↗
NASA NTRS1975

Scanning system tradeoffs for remote optical sensing from geosynchronous orbit

The scanning and telescope field of view requirements for making Earth Resources (ER) and Meteorological (MET) phenomena observations from a Synchronous Earth Observation Satellite (SEOS) have been defined. The equations relating spacecraft scan capability to user scan field of view requirements are given and evaluated using four different telescope fields of view. The tradeoffs between telescope field-of-view and user scan fields of view requirements are shown, and it was determined that a 0.6 degree by 1.2 degree telescope FOV is optimum for the SEOS telescope. It was shown that an internal scan as well as external scan is required to satisfy both ER and MET users.

Young, P. J.↗
NASA NTRS1979

Studies of magnetostriction and spin polarized band structures of rare earth intermetallics

Anisotropic magnetostriction measurements of R6Fe23, R = (Tb, Dy, Ho, and Er) were carried out from 77 K to room temperature. Magnetic fields up to 2.1 Tesla were applied. All the compounds exhibited large magnetostrictions at 77 K, the largest effect being obtained for Tb6Fe23. Saturation magnetostriction values for the compounds were also determined for 77 K and room temperature. Results of the temperature dependence of magnetostriction for Er6Fe23 are in good agreement with Callen and Callen's single ion theory. Therefore, the main sources of magnetostriction in this compound is the Er ion. The spin-up and spin-down electronic energy bands, the density of states and the magnetic moments of YCo5, SmCo5, and GdCo5 were calculated by the spin polarized augmented plane wave technique. The calculations obtained show the origin of the moment, provide good estimates of its magnitude and variation, and the reasons for those variations. They also show the important role of partial charge transfer and of d-d electronic coupling. Calculations for LaNi5 and GdNi5 systems are discussed.

Wallace, W. E.↗
NASA NTRS1978

Ephemeral region flares and the diffusion of the network

Flarelike events which are frequently observed in H-alpha in apparently quiet regions of the solar disk can be in all cases identified with bipolar ephemeral regions (ER) on magnetograms. These events represent the H-alpha counterpart of X-ray bright point flares. Statistically, this phenomenon is associated with the proximity of the bipolar features to the supergranulation network in the sense that an ER is likely to flare during its lifetime if the distance to the nearest network element is less than or equal to its own pole separation.

Marsh, K. A.↗
NASA NTRS1980

A statistical determination of the shape and position of the geomagnetic neutral sheet

Using 2.5-minute average field values from Imp 6, 7, and 8 magnetic field measurements, the standard magnetotail neutral sheet (MNS) model is examined. The best representation for the MNS is found to be an arched surface which crosses the solar magnetospheric equatorial plane on the flanks of the tail about 18 earth radii (ER) from the tail axis; the surface is anchored to the geomagnetic dipole at a hinging distance of 10.5 ER. In addition, the shape and position of the neutral sheet (NS) do not vary significantly with distance down the tail, but the NS is anchored somewhat closer to the earth during disturbed geomagnetic conditions.

Fairfield, D. H.↗
NASA NTRS1980

Mn-53 and Al-26 evidence for solar cosmic ray constancy - An improved model for interpretation

A general, numerical method for calculating activities of solar cosmic ray produced radionuclides at any point within an irregularly shaped lunar rock of known surface contour and lunar surface orientation is described. This method is then used to predict the activities of Mn-53 andAl-26 as a function of postion within lunar rock 68815 for various assumed values of solar cosmic ray flux (J), rigidity (R sub 0), and rock erosion rate (ER). The predicted activities agree with the measured activities of Kohl et al. (1978) when values of R sub 0 = 100 MV, J = 70 p/sq cm-sec (4 pi, E greater than 10 MeV), ER not greater than 1 mm/m.y. and a total exposure time of 2 m.y. are assumed. These values are in agreement with those found for rocks exposed for not less than 10 m.y. and provide no evidence for variation of the average solar cosmic ray parameters between the last 2 and 10 m.y. intervals. When interpreted with the improved model the activity vs. depth profiles for three faces of 68815 show no evidence of SCR anisotropy or differential erosion.

Russ, G. P., III↗